Elastic fluid engine



Feb. 16, 1932.

s. e: KNOX 1,845,288

ELASTIC FLUID ENGINE Filed Aug. 5, 1927' 5 Sheets-Sheet I 8 INVENTOR $3 5. K4, MK

Feb. 16, 1982, S. L. G. KNOX 1,845,288

ELASTIC FLUID ENGINE Filed Aug. z. 1927 5 Sheets-Sheet .2

v I R? w QI sz/llrqlE NToR I ATTORN EYS Feb. 16, 1932. s. L? G. KNOX 5, I

ELASTIC FLUID ENGINE Filed Aug. 3. 1927 5 Sheets-Sheet 3 w M \i. wnna Feb. 16, 1932. s. G. KNOX 1,845,283

ELASTIC FLUID ENGINE Filed Aug. 3. 1927 5 Sheets-Sheet 4 ATTORNEY5 m 7/ wi l! ll l/lllllli v r lan Feb. 16, 1932. s. L. G. KNOX 1,845,288

' ELASTIC FLUID ENGINE Filed Aug. 3, 1927 5 Sheets-Sheet 5 FORWARD RVERE STEAM Q9 up I M 53 5A .ar C3 INVENTOR 9%; X4, /mo I Forward DiICCTI OI'L Reverse Di ection A'QIZM-VQ'N 1 ATTORNEYS Patented Feb. 16, 1932 pairs D STATES "PATENT OFFICE SAMUEL LIPPINGOTT GRISWOLD KNOX, ENGLEWOOD, NEW JERSEY nnesrrc FLUID ENGINE Application filed August a, 1927. Serial No. 210,281.

was well as the forward, direction at frequent intervals.

Amongthe objects of-the invention 1s the provision of a fluid-pressure engine that 1s capable of reversing its direction of rotation with small likelihood of damage to itself, and with a minimum of effort on the part of the operator.

- Another object of the invention is to provide an engine in which the direction of rotation is reversed by valves in the steam admission line, thereby eliminating link mechanism or its equivalent.

Another object of the invention is to 0b-- tain reversal. of the direction of rotation withoutaffecting the valve setting, and thereby making cutoflf economies possible.

Another object is to obtain reversal of rotation without afl'ecting the valve-setting or changing the valve-driving mechanism, thus 3.) simplifying the construction and avoiding the duplication of. parts.

Another object is to vprovide a slide-valve I in.which the relative position of the slide and the element which actuates it, is auto-.

' matically determined. by the point of entry of the motive-fluid into the valve-chamber.

I Another object is tocombine with athrottle valve a relief valve of simple and novel construction, the'relief valve being located in the stem ofthe throttle valve, and bein automatically opened by the element whic closes the throttle valve. The'manner of reversing the direction of rotation of the improved engine is one of its important features. In accordance with the invention the engine is provided with a plurality of cylinders and a plurality of valves. The valves are connected to the cylinders by passages for the operating fluid, these paszu. sages being arranged in such manner that when the engine is operating, let us say, in the forward direction of rotation, each cylin-. der is controlled by a given valve, but when the direction of rotation is reversed, each cylinder is controlled by a difl'erent valve.

' In order to illustrate the principles of the invention by way of a specific example, the invention will be described as applied to a 3-cylinder steam engine of the uniflow type which is illustrated in the accompanying co' drawings and which is adapted to operate a steam shovel. The principles of-the invention, however, can be applied to fluid pressure engines other than uniflow engines. Moreover, the principles of the invention may be employed in constructing engines adapted to operate by means of any desired fluid pressure. The particular engine illustrated in the accompanying drawings can be operated by steam, compressed air or the like.

In these drawings: Fig. 1 is a vertical longitudinal section taken on line 11 of Fig. 3 showing cylinder A and piston valve a in section.

Fig. 2 is an enlarged section taken longitudinally throughvalve a.

Fig. 3 is a view partly in central horizontal section and partly in plan of the engine shown in Fig. 1, the section being taken on the broken line 3-3 of Fig. 1.

Fig. 4 is a transverse vertical section taken on the line 1et of Fig. 1 showing the exhaust ports.

Fig. 5 is a plan of the exhaust manifold. Fig. 6 is a longitudinal and horizontal section taken centrally of the valves on broken line 66 ofFig. 1. i r Fig. 7 is a section taken on lines 77 of Figs. 3 and 6 showing one of the eccentrics and the rockers for actuating valves 6 and 0. Fig. 8 is "a detailed section taken on line 8-8 of Figs. 6 and 12 showing in dotted lines the steam ducts connecting the steam chests at the center of the valves for operatingin the forward (clockwise) direction of rotations all referring to Fig. 4, vFig. 13 being taken on line 1313, Fig. 14 on line 14 14, 15 Fig. 15 on line 1515 and Fig. 16 on line Figs. 17 and 18 are diagrammatic cross-sectional views of the cylinders and valves, Fig. 17 being taken along the central line 1717 20 of the outer inlet ports and passages as shown in Figs. 13 to 16 inclusive and Fig. 18 being taken along the central line 1818 of the inner inlet ports and passages as shown in Figs. 13 to 16 inclusive. Fig. 17 shows the connections of the valves and cylinders throughthe outer ports and passages at one end and Fig. 18 shows the connections of the valves and cylinders through the inner ports and passages at one end. The connections at both ends are identical.

Figs. 19 to 21 inclusive are diagrammatic 1 sectional views of the respective positions of the pistons, valves, and eccentric when steam is admitted for forward rotation.

Figs. 22 to 24 inclusive are diagrammatic sectional views of the cylinders and valves in their'new relation to each other, and the eccentric control, in reverse direction of rotation. J

Figs. 25 and 26are-diagrammatic views showing port and passage connections between the valves and cylinders in the forward and reverse directions. i

The three-cylinder reversing steam-engine, referring to Figs. 1, 3 and 6, comprises three cylinders A, B, C, with corresponding pistons 43, 44, 45, of the uniflow type, their corresponding piston rods 30, 31, 32, joining the pistons to their corresponding cross heads 33,

connecting rods 36-, 37, 38, connect the cross heads to the crank pins 39, 40, 41, of the crank shaft 42. Two eccentrics 46, 47, are 1 carried on crank shaft 42, and three piston valves (1, b, c, controlling cylinders A, B, C. are actuated by the eccentrics 46, 47.

' The engine bed 48 supports and completely encloses crank shaft 42 together with the piston valves controlling mechanism (to be described in detail later) and cross-heads 33, 34, 35. The engine bed is cast so as to form the cross-head guides 49, 50, 51 The stufiing boxes 52, 53, 54, seal the openings in the vertical wall for piston rods 30, 31, 32, in the cylin- 55 der end-of engine bed 48. The removable proJection 81.

34, 35, which are .cylindrical in form. The

plates 55,56, are provided in the vertical walls.

of engine bed 48 to allow easy access to interior of the engine bed. The engine bed 48 is \fur ther cast with/flanges 57, 58, shown in Figs. 1 and 3, supported by webs 59, 60, extending within the engine bed, as shown in Fig. 1.

The members 61, 62, are secured to flanges 57, 58, by bolts 63. The member 61 and flange 57 encase a roller bearing 64 at the left end of crank shaft 42 while member 62 and flange 58 encase a roller bearing 65 at the right end. of the crank shaft. I

The'two. lateral thrust bearings 66, 67, seal the openings for crank shaft 42 in the vertical walls of engine bed 48. The packing rings 68,

69, of thelateral thrust bearings 66, 67 act on the outer faces of roller bearings 64, 65'. The crank shaft rotates freely between lateral thrust bearings 66, 67. The engine bed 48 has a removable cover 7 0 shown in Fig. 1. This removable cover is fixed to the engine bed by bolts 71. 1 f

The members 61, 62, support a rod 72 which is encased by a hollow shaft 73. This shaft 73 has two arms 74, 75, projecting at right angles to its axis and fixed to members 61, 62, by bolts 76, 77. In this manner the rotation of hollow shaft 73 around rod 72 is prevented. Two other arms 78, 79, forming an integral part of shaft 73 are fixed in position and de- "pend from this shaft iii the same vertical planes as the eccentrics46, 47-respectively. These arms-7 8, 79, are forked at their lower extremity.

Referring particularly to Figs. 1 and 3, the eccentric 46 is encircled by an eccentric strap 80. This eccentric strap has a forked A valve stem rocker 82 of triangular shape passes between the tongues at the lower extremity of arm 78 and is pivotably attached'to arm 78 by a pin 83. The rocker also passes between the tongues of projection 81 andis fixed thereto by a pin 84. The rocker is also attached to valve stem of valve a by means of a in 86. The rocker 82 transmits the motion of the eccentric strap to valve stem by pivoting around pin 83in fixed arm 78. i

The eccentric 47 referring particularly to Fig. 7 is enclosed by an eccentric strap 87 which has two forked projections 88, 89. A valve stem rocker 90 passes between the tongues in fixed arm 79 andis pivotally attached near its center to the fixed arm by a pin 91-. One of the ends of rocker 90. passes between the tongues of projection 88 and is fixed thereto by a pin 92. The lower end of the rocker is attached to valve stem 93of valve 0 by means of a pin 94. The rocker transmits the motion of the eccentric strap to' valve stem by pivoting around pin 91 in fixed arm 79.

Referring again to the two members 61, 62,

which support fixed shaft 73, these two members also support a rod 95 upon which a hollow rock shaft 96 oscillates. An arm 97 integral with shaft 96 projects therefrom in the same vertical plane as eccentric 47. The tongues of forked projection 89 on the eccentric strap 87 are pierced by a pin 98 having an aperture at right angles to-the axis of the pin. The extreme end of arm 97 fits into the aperture in pin 98 thereby forming a sliding joint between arm 97 and eccentric strap 87. This sliding joint will transmit the motion of the eccentric strap to shaft 96 giving the shaft a rocking motion.

From hollow shaft 96 depend two arms 99-100 which are attached respectively by pins 101, 102to the two rods 103, 104. A cross-bar 105 is attached to the ends of rods 103, 104, said cross-bar being connected at its center between rods 103, 104 to the valve stem 106 of valve 6. In this way the rocking motion of shaft 96 is transmitted to valve stem 106. The cross-bar 105 has a forked projection atone end which loosely gripsthe valve rod 85 thereby preventing the cross-rod from rotating around the valve stem 106.

5 Referring now particularly to Fig. 6, valve stems 85, 106, 93 pass through the cylinder end vertical wall of the engine bed'48, and are sealed by stutfing boxes 107, 108, 109.

. As I have already remarked, engine bed 48 completely encloses the crank shaft, crossheads, eccentrics,'part of the valve stems and piston rods, and the different rockers and arms for transmitting the motion of the eccenrics.to the valve stems. Being completely enclosed, these parts may be lubricated by splash lubrication and the parts are protected from dust, and other injurious external influences.

The cylinders A, B, O, and valves a, b, c,

are connected to engine bed 48'and supported by bolts 110 and lugs 111, 112. The cylinders A, B C, are of usual construction with cylinder eads 113, 114, the heads 114 being supplied with stufling boxes 115 for the piston rods 30, 31, 32. I

The exhaust ports 116 are situated at the center of the cylinders and are clearly shown in Fig. 4. In Fig. 5 the exhaust manifoldis shown. The inlet passages'open' into the cylinders at either end of the cylinders. I will leave the description of the inlet ports and passages until I follow the path of the steam.

The piston valves a, b, c, (valve'a being shown in Fig. 2) comprise the friction or wearing sleeves 117, the valve heads 118, 119, the heads 119 being supplied with stufiing boxes 120 for the'valve stems 85, 106, 93. All three valves are identical in construction and an enlarged view of valve a is shown in Fig. 2. The piston valves are really double piston valves, each valve having two inner inlet ports 141 and two outer inlet ports 142. The port controlling pistons 121, 122, 123, of the valves (1, b, c, consist of two controlling portions formed by the similar sleeves 125, 126 mounted in axially movable relation upon the valve stem. The outward movement of the movable sleeves .125, 126, is limited respetively by the enlargement 124 at the crank in reversing the engine. The two movable sleeves 125, 126'which comprise the two port controlling portions of the pistons are capable of a short lateral translation on the valve stem as described. A spring 130 encircling the centrally enlarged portion of sleeve 127 acts against the inner ends of the movable sleeves 125, 126, and tends to keep them firmly in position, and preventsany banging back and forth of these parts when not held in fixed relative position by the admission of steam. This spring is not strong enough to resist the change of relative position when the parts are acted on by steam.

Having described the various operative elements I will now follow the path of the steam through the engine.

The steam enters the steam passage 131 (Figs. 4, 12) situated below the cylinders and valves. This passage 131 adjoins two similar passages 132, 133, as shown in Fig. 12. In passages 132, 133, are situated spring and pressure seated throttle valves 134, 135. Fig. 10 shows a section through throttle valve 135. A shaft 136 situated at right angles to the axis of valves 134, 135, and having its axis slightly below the axis of the valves has a crank pin 137 projecting from the end of shaft 136 nearest the valves, the pin 137 being slightly off center so as to be in the same horizontal plane as valves 134, 135. By rotating shaft 136, the pin 137, being ofif' center, acts on the valve stem of one of valves 134, 135, thereby opening the valve. In the position indicated in Fig. 12 both the valves are closed. On rocking shaft 136 to the left by means of a throttle handle 136a. valve 134 will be opened. thereby operating the engine in the forward direction of rotation and on rocking shaft 136 to the right valve 135 will be opened so as to operate the engine in the reverse direction.

I will now follow the path of the steam in 136a to the left valve 134 will be opened thereby admitting steam from passage 132 a to passage 138. Passage 138 is shown leavthe center of the valves in Fig. 8. Passage Q inner inlet ports of valve a.

138 is also shown in dottedlines in Fig. 6.'

The central steam chests 139 are connected by ducts 140 (Figs. 6 and 9) so that steam will flow from passage 138 to the centers of all three valves.

The steam on entering the central "steam chest forces movable sleeves 125, 126 outward as shown in Fig. 2. In this position the movable sleeves uncover only inner inlet ports 141 during the entire travel of the valve pistons while the outer inlet ports are maintained closed.

In the forward (clockwise) direction of rotation'the inner inlet ports 141 of the valves a, b, 0, are connected to cylinders A, B, C, by the passages aA, 6B, 00, as shown diagrammatically in Fig. 25.

Figs. 13 to 16 inclusive are sectional views showing the inlet ports and passages connecting the cylinders and the valves. These sections all refer to Fig. 4 which is a cross-sectional view of valves and cylinders, Fig. 13 being taken on line 1313, Fig. 14 on line 1414 etc.

Figs. 17 and 18 are diagrammatic cross-sectional views of the cylinders and valves, Fig. 17 being taken along the central line 1717 of the outer inlet ports and passages at one end as shown in Figs. 13 to 16 inclusive and Fig. 18 being taken along the central line 18-18 of the inner inlet ports and passages at opposite ends as shown in Figs. 13 to 16 inclusive.

I In the forward direction of rotation, as I have remarked, only the inner inlet ports 141 are uncovered during the entire travel of the valve pistons, the outer inlet ports 142 remaining closed. As shown in Fig. 25 the inner inlet ports 141 of valve a are connected to cylinder A by the passages aA. In Fig. 15 the passages (1A are shown just as they leave the In Fig. 13 the passages aA are shown connecting with the passages'bA, the joint passages aA, bA leading into the cylinder A. In Fig. 18 the passages (LA and 6A are shown joining into each other and leading together into the cylinder A. It is to be noted that the passages 6A are connected to the outer inlet ports ofthe valve 1) and therefore steam flowing from valve or through passages aA into cylinder A will not flow into valve 6 because the outer inlet ports are always sealed in the forward direction of rotation.

As shown in Fig. 25 the inner inlet ports 141 of valve 1) are connected to cylinder B by the passages 6B.

In Fig. 14 the passages 5B are shown leaving the inner inlet ports of valve 1) and joining the passages B. the joint passages 6B, 013 leading into cylinder B. The passages 0B are connected to the outer inlet ports of valve I; but as these are closed in the forward direction of rotation no steam will flow into valve 0 as steam is admitted into cylinder B from valve 6 throu h the passages bB.

In Fig. 17 t e passages 0B are shown joining into the passages 12B and thence leading into cylinder a The inner inlet ports 141 of valve 0 are connected to cylinder C as shown in Fig. 25 by the passages 0C. In Fig. 16 the passages 0C are shown leaving the inner inlet ports of valve 0, and leading into cylinder Q. Passages 0C are also shown in Fig. 18. It is to be noted that passages aC also lead into cylinder C but the passages connect with the outer inlet ports of valve a which are always closed in the forward direction of rotation and therefore no steam will escape from cylinder G into valve (1 as steam is admitted to cylinder C from valve 0 through passages 0C. Passages cC are also shown in Fig. 18. The steam after expansion in the cylinders passes out of the cylinders through exhaust ports 116, shown in Fig. 4 and into exhaust manifold (Figs. 4 and 5.)

Returning now to Fig. 12, by rocking shaft 136 until pin 137 is in its central position both valves 134, 135 will be closed and no steam will be admitted to the engine. 4

I will now follow the path of the steam in the reverse direction. If the throttle handle 136a is moved to the right valve 135 will be opened thereby admitting steam from passage 133 to conduit 143 which is shown leaving the throttle valve in Fig. 12. Conduit 143 opens into a passageway 144 which leads to the ducts 145 at either ends of the valves. Conduit 143 is shown in dotted lines in Fig. 4 opening into passageway 144 and this opening is shown in Fig. 9. In Fig. 9 the passageway 144 as well as the ducts 145 at either ends of the valves are shown. In Fig. 6 these ducts 145 running transversely of the valve casting connect the steam chests 146 which are situated at the ends of valves a, b, 0.

Referring to Fig. 2 the. steam after having passed through conduit 143, passageway 144 and the-ducts 145 enters the end steam chests of the valves and forces movable sleeves 125, 126 inward toward the center of the valves. In this position the movable sleeves will uncover only the outer inlet ports 142 during the entire travel of the piston, while the inner inlet ports 141 will always be closed. a

In the reverse direction, the outer inlet ports of valves a, b, c, are connected to cylinders C, A, B, respectively by passages (10, A. and 0B as indicated diagrammatically in Fig. 26. The lettering of the passages indicate which valve and cylinder they connect together.

- As indicated in Fig. 26, valve (1 is connected to cylinder C and in Fig. the passages aC are shown leaving the outer inlet ports of shown in Fig. 17 and both passages 11C in Fig. 13

' Valve bis connected to cylinder A as shown in Fig. 26 and in Fig..,13 passages 6A are shown leaving the outer inlet ports of valve .6 'andjoining into passages (1A, the joint passages aA, 6A leading into cylinder A.

- We have already seen that passages aA connect' the cylinder-A to inner' inlet ports of valve a but as these inner ports are alwa s closed in the reverse direction steam may e admitted to cylinder A from valve 6 through the pasages bA without allowing steam to enter valve a. Two other views of passages 6A are shown in Figs. 17 and 18.

Valve 0 is connected to cylinder B according to Fig. 26 and in Fig. 16 the passages 0B are shown leaving the outer inlet ports of valve 0 and in Fig. 14 the passages cBare shown joining with passages 6B, the joint passages'bB, 0B leading into cylinder B. As previously mentioned passages bB connect cylinder B with the inner inlet ports of valve 12 but as these inner ports are always closed in the reverse directlon no steam can enter the valve 6. Steam will be admitted into-cylinder B from the valve 0 through outer inlet ports and the passages 0B. One of the passages cB is shown in full-in Fig. 17. The

I handle 136a is rocked to'the right valves a, b,

c, are connected to cylinders C, A, B, respectively, thereby reversing the direction of the A engine. In other words, the valves'a're connected to the cylinders by inlet ports and pas- .sages,each valve Having inner inlet ports and passages leading to a cylinder and outer inlet ports'and passages leading to a differentcylinder. These inlet ports are controlled by valve pistons with movable sleeves. These movable sleeves are so arranged that only,

the inner inlet ports are opened when steam is admitted to central steam chests and that only theouter inlet ports are opened when steam .is admitted to end steam chests. The engine therefore may be stopped or reversed by simply rocking the throttle handle 136awhich controls by means of throttle valves 134,135 the, admission of steam to the steam chests. The valve settings are not afiected by these changes due to the two sets of ports in each valve and the movable sleeves 125, 126 which automatically adjust themselves under the action of the steam so as to close one or the other of the sets of ports. As we have seen, the outer inlet ports are closed when steam is admitted to the central steam chests and the inner inlet ports are closed when dmitted to the end steamchests 146.

steam is a In orderto obtain this result it is impor-- tant that when steam is admitted to the central steam chests that there should be substantially no pressure in the end steam chests 146 and vice versa when the direction of the engine is reversed. This is accomplished by tened at its sides to allow for the passage' of steam. The inner end of the needle is pointed and is adapted to close a small opening 148 in the valve stem. Opening 148 connects wit an aperture 149 which pierces the part of the valve stem lying in the passage 143 leading to the end steam chests of the valves. beyond the end of the valve stem so that the crank pin 137 will act directly on the needle valve 147.

When the handle 13611 is rotated to the right the crank pin 137 will bear on the needle valve, opening valve 135 but also closing the opening 148, the pointed end of the needle, due to the pressure of crank pin 137, bearing against the passage 148 and thereby closing left the valve 135 automatically closes. 'As the crank pin is no longer acting on the needle valve any steam in passage 143 will force its way through the opening 148 and past the needle. This requires very little pressure as The needle valve 147 projects it. When the handle 136a is rotated to the the needle is loosely fitted in the valve stem.

The flattened surfaces of the needle furnish free spaces 150, as shown in Fig. 11, between the needle and the valve stem so that both steam and any condensation may flow to the end of the valve stem and out of the valve.

body at151. This exit is accessible to steam from passage 143 when throttle valve 135 is closedand therefore no pressure can build up in the end steam chests while steam is being admitted to central steam chests by throttheir respective throttle valves 134, are

closed and therefore prevents any building up of pressure in the steam chests which are to illustrate diagrammatically the various moving parts of the engine in relation to each other.. Figs. 19, 20, 21 show the corresponding positions of the eccentrics, rockers, valve stems and valve istons for a certain position of the pistons of the cylinders when the engine is running in the forward direction. Figs. 22, 23, 24 show the relative positions of the same parts when the engine is running in the reverse direction.

'As I have already mentioned the crank shaft carries two eccentrics. These two eccentrics are in alignment, which is the same thing as having one eccentric. Two eccen-' trics are used, however, because a better balanced relationship of the crank shaft is obtained and also because a more complicated link mechanism would be required with one eccentric.

The eccentric 80 illustrated diagrammatically in Figs. 19 and 23 operates a single valve while the other eccentric operates, through a rock shaft and linkage connection, the other two valves. The rockers constituting the linkage between the valve stems and the eccentrics are connected to the eccentrics at points situated apart. The rocker shown in Figs. 20 and 24 reversing the motion of the eccentric so that the valve stems are actuated in the same manner as if they were driven by three different eccentrics having their centers 120 apart.

The advantages of fractional cut-off are obvious. By cutting off the steam supply to each cylinder at a portion of its stroke, the expansive force of the steam already in the cylinder is utilized to continue the drive, without drawing on the boiler for any more -live steam, thus accomplishing a considerable saving of steam. To have a fractional cut-01f in a reversable engine, as hereto-fore built, always required a shifting of the eccentrics when reversing. My invention, by transferring each valve to, a different cylinder when reversing, accomplishes this same ,end without the necessity of the complication of shiftable eccentrics. Thus; in a threecylinder engine I obtain what is known as one-third cut-off, thatis tosay a cut-off at one-third of the stroke, i. e. 60 rotation.

. The same principle would beapplicable to a two-cylinder engine with one-half out-ofi', a four-cylinder engine with one-quarter cutoff, or an nth-cylinder engine'with one-nth cut-oft.

it is to be understood that 'my invention is' applicable to engines driven by. any other form of expansible fluid pressure.

Claims to the relief valve feature shown 1n this application are included in my copending application, Serial No. 288,151, filed une 25, 1928, for improvements in throttle valves.

I claim:

.1. A reciprocating fluid-pressure engine comprising: a plurality of cylinders; with their accompanying pistons, piston-rods and connecting rods; valves connected to said cylinders by inner and outer ports and passages, the inner ports and passages connecting a valve to one of the cylinders, the outer ports and passages connecting the same valve to a different cylinder; and means for closing only the outer ports in one direction of shaftrotation, said means closing said inner ports and opening said outer ports in the opposite directlon of sha ft-rotation so that said valves serve to control different cylinders in opposite directions of rotation.

2. A reciprocating pressure-fluid engine comprising: a plurality of cylinders; with their-accompanying pistons, piston-rods and connecting rods; valves connected to said cylinders by inner and outer ports and passages, the inner ports and passages connecting a valve to one of the cylinders, the outer ports and passages connecting the same valve to a different cylinder; and pressure actuated means associated with said valves for selectively closing the inner and outer ports so as to cause said valves to control different cylinders and thereby the direction of rotation ofthe engine.

' 3. A reciprocating fluid-pressure engine comprising: a plurality of cylinders; with their accompanying pistons, piston-rods and connecting rods; plston valves having center and end fluid chambers associated therewith, said valves being connected to said cylinders by ports and passages, each valve having inner inlet ports and passages connecting it to a cylinder, and outer inlet ports and assages connecting it to a. different cylin er; fluid-pressure actuated sleeves coacting with the pistons of each valve, said sleeves acting to maintain the outer inlet ports closed when fluid is admitted to said central fluid chambers and acting to maintain the inner inlet ports closed when fluid is admitted to said endfluid chambers; and means for controlling the admission of fluid to said fluid chambers so that the direction of rotation may be reversed by actuating said means.

. 4. A reciprocating fluid-pressure engine comprising: a plurality of cylinders: with their accompanying pistons, piston-rods and connecting rods; piston valves having central and end fluid chambers associated therewith,

said valves being connected to said cylinders by ports and passages, each valve having inner inlet ports and passages connecting it to a cylinder, and outer inlet ports and passages connecting it to a different cylinder, fluidpressure actuated sleeves coacting with the pistons of each valvefi-said-sleeves acting to maintain the outer inlet, ports closed when fluid isadmitted to said central fluid chambers, and acting to maintain theinner inlet ports closed when fluid is admitted to saidend fluid chambers; auxiliary valves'for controllingadmission of fluid to said central and end fluid chambers; and means for actuating sa1d auxiliary valves to open only one of said auxiliary valves at a time.

5. In a slide-valve for reciprocating fluldpressure engines, the combination of: a fluid chamber; a plurality of ports for admitting the motive fluid thereto; a ported valve seat in said chamber; a slide cooperating with said seat; and means for reciprocat ng said sl de; said slide and said means being characterized by the fact that,'when one set of admis-.

sion ports is used, said slide occupies one positionrelative to sa1d means, and when another set of admission ports is used, sa1d slide occupies a diflerent position re1at1ve to said means.

6. In a fluid-pressure engine sllde-valve, the combination of: a fluid-pressure chamber, hating at least'two points for the entry of fluid thereto; a valve-seat in said chamber; a slide coacting therewith; and an element for reciprocating said slide; the parts being so contrived and disposed that the relat ve position of said slide and said element is 1n'- fluenced by the point of entry of the fluid.

7. In a fluid-engine slide-valve, the comblnation of: a compound fluid-pressurechamber; two openings to lead the fluid into sa1d chamber; means to select wh1ch of these openings is to be used for this purpose; a plurality of ports to lead the fluid from saidchamber; a reciprocatable slide within said chamber, operable to open andclose sa1d port-s selectively; and a reciprocatlng element to reciprocate said slide; the relative position of saidslide and said element being determined by the fact that, when one set of admission ports is used, said slide occuples one position with respect to said element, and

when another set of admission ports is used, said slide occupies a different position relative to said element.

8. In a reciprocating fluid-pressure engine,

a piston valve comprising: a cylinder; end 7 fluid chambers; a central fluid chamber;

inner and outer ports at either end ofsaid cylinder; a valve stem extendingtwithin said cylinder; means for imparting a reciprocating motion to said valve stem, sleeves slidably mounted on said valve stem at either end of the cylinder, said sleeves having a limited axial motion on the valve stem, said sleeves being forced inward when fluid is admitted to said end fluid chambers so that only the outer portsare opened during the reciprocatto said central fluid chamber so that only the inner ports are opened during the reciprocatingmotion of said valve stem; and means for controlling admission of fluid to said fluid chambers.

9. In a reciprocating fluid-pressure engine: a plurality of cylinders; pistons for said cylinders; connecting-rods for impartingithe motion of said pistons to a. crank shaft, slide valves for controlling admission of fluid to said cylinders, eccentrics on said crank shaft and driving/means for connecting said eccentrics and said valves'to give theengine a predetermined valve-lead; and fluid-responsive means on said valves for reversing the valve lead so that the, direction of rotation of the engine may be reversed.

' 10. A reciprocating fluid-pressure engine comprisingza plurality ,of cylinders; piston valves having central and end fluid chambers associated therewith, said valves being connected to said cylinders by ports and passages, each valve having inner inlet ports and passages connecting it to a cylinder and outer inlet ports and passages connecting it to another cylinder; valve'pistons having mova-' for controlling the admission of fluid to said fluidchambers; and means for relieving the pressure from the chambers to which fluid is not being admitted.

11. A reciprocating fluid-pressure engine comprising: a plurality of cylinders; piston valves having central and end fluid chambers associated therewith, said valves being con-- nected to said cylinders by inlet ports and passages, each valve having inner inlet ports and passages leadlng toa cylinder and outer inlet ports and passages leading to another 7 cylinder; valve pistons having movable portcontrolling sleeves coacting therewith, said movable sleeves being actuated by fluid pressure to cause only the'inner inlet ports to be opened when fluid is admitted to said central fluid chambers and to cause-only the outer inlet ports to be opened when fluid is admitted to said end fluid chambers; a throttle valve for controlling admission of fluid to said centralfluid chambers; a throttle valve for controlling admission of fluid'to, said end fluid chambers; fluid-pressure escape valyes cooperating with said throttle valves where by the pressure is relieved from the fluid pressure chambers to which fluid is not being admitted; and means for actuating said throttle valves whereby only one of said 'nected to said cylinders by passages; revers ing means; means, responsive to the direct action of the reversing means, for causing each cylinder to be controlled by one certain "alve; and means, responsive to the reverse action of the reversing nieans, for causing each cylinder to be controlled by one certain other valve.

13. A reciprocating fluid-pressure engine,

comprising: a plurality of cylinders, with their accompanying pistons, piston-rods and connecting rods; a crank-shaft, valves for the cylinders, each valve being connected to two of said cylinders'by two separate groups of passages; and means for rendering active said group of passages selectively, so as to cause each valve to control one cylinder in one direction of shaft-rotation, and a different cylinder in the opposite direction of shaft-rotation.

14. In a fluid-pressure reciprocating engine, the combination of: a plurality of fluid cylinders, with their accompanying plstons,

I piston-rods and connecting rods; a crank shaft; valves, to a number equal to that of thecylinders, to control the intermittent acimission of motive-fluid to the cylinders, each valve serving one cylinder only for any one direction of rotation of the shaft; means whereby, when the shaft is rotating in one direction, each valve serves one certain cylinder, and" means whereby, when the shah, is rotating in the opposite direction, each valve serves one certain other cylinder.

15. In a fluid-engine slide-valve, the combination of a compound fluid-pressure chamber; two openings to lead the fluid into said chamber; means to select which of these openings is to be used for this purpose; a p u plurality of ports to lead the fluid from said chamber; a reciprocatable slide within said chamber, operable to open and close said ports selectively; a reciprocating element to reciprocate said slide; the relative position tion, and when another set of admissionports is used they occupy a difierent relative position; and dashpot meansinterppsed between said reciprocating element and said reciprocatable slide.

17. In a fluid-engine slide-valve, the combination of a compound fluid-pressure chamher; two openings to lead the fluid into said chamber; means to select which of these openings is to be used for this purpose; a plurality of ports to lead the fluid from said chamber; a reciprocatable slide within said chamber, operable to open and close said ports selectively; a reciprocating element to reciprocate said slide; the relativeposition of said slide and said element being so determined that when one set-of admission ports is used they occupy one relative position, and when another set of admission ports is used they occupy a different relative position; means to hold'said reciprocating element and said reciprocatable slide in fixed relation with respect to each other when fluid is not being admitted into the. chamber; and dashpot means interposed between said reclipirocating element and said reciprocatable s 1 e. 1 a

1 In testimony whereof I affix my signature.

4 SAMUEL LIPPINCOTT GRISWOLD KNOX.

rality of ports to lead the fluid from said tion; and means to hold said-reciprocating element and said reciprocatable slide in fixed relation with respect to each other when fluidis not being admitted into the chamber.

16. In a fluid-engine slide-valve, the combination of: i a compound fluid-pressure chamber; two openings to lead the fluid into said chamber; meansto select which of these openings is to be used for this purpose; a 

